The invention relates to a plant for the production of calcium carbide by melting and reducing a burden comprising CaO or CaCO.sub.3, by supplying electric energy to a melting furnace having a melting space with a plasma burner means and supply means for the burden components.
Hitherto, graphite or Soderberg electrodes with large diameters have commonly been used to supply the electric energy. With these electrodes, no freely burning arc was formed, and the heating was effected substantially by resistance heating of the burden. Correspondingly, the temperatures which could be reached in the melting region were relatively low and the time required for melting was correspondingly long.
A method of forming a plasma arc is known from U.S. Pat. No. 3,404,078, in which a fluidized bed of electrically conductive particles constitutes one electrode, and a plasma arc burns between the fluidized bed and a second electrode. for the production of CaC.sub.2 a fluidized bed of graphite particles suspended by means of argon is disclosed. Calcium oxide is supplied to the plasma region with an argon carrier gas flow and agglomerates of carbide-coated graphite particles are obtained. To obtain the CaC.sub.2, further complex treatment of the solid agglomerates formed is necessary, which is connected with losses of graphite. The degree of reaction of the graphite carbon with the CaO is very low, thus the CaC.sub.2 production according to the method disclosed in U.S. Pat. No. 3,404,078 is not economical.
The present invention aims at avoiding the disadvantages described of known methods, and has as its object to provide a plant in which temperatures substantially higher than those occurring with resistance heating are achieved, resulting in a rapid operationally safe melting and a quick and complete reaction between the burden components. The invention further provides a plant, in which the development of the reaction is controlled in an improved manner and in which the uncomplicated preparation of very pure CaC.sub.2 is possible.